n6 



NA TURE 



\June i, 1882 



Page 1 (1876). — The regulating arrangement is the following : 

 A piece of glass tube about seven-sixteenths of an inch diameter 

 and \\ inch long is fitted at one end with a short round cork ; 

 through the centre of this cork a hole is bored, so that the stem 

 of the thermometer just fits in it ; the other end of this glass 

 tube is closed by a short tightly-fitting india-rubber cork, which 

 is pierced by a fine brad-awl through its centre. Into the hole 

 thus formed is forced a piece of fine glass tubing three inches 

 long and small enough to fit loosely inside the stem of the 

 thermometer. The gas enters by this fine tube. 



Fletcher 2 (1876) stated that he had for some time used a 

 similar regulator, but that the thermometer had an iron bulb 

 capable of containing two or three pounds of mercury. He also 

 reversed the direction of the gas. 



Mercurial Thermometers (6). — Scheibler 3 (1S65) devised the 

 following arrangement. In the bath or chamber which is being 

 heated is placed an electric thermometer ; this communicates 

 with an electro-magnet which is inclosed in a small metallic 

 chamber through which the gas for the burner has to pass. 

 When by a rise in temperature the circuit is closed, the 

 hinged armature of the magnet is brought into contact with the 

 opening of the gas inlet-tube, and is not liberated until a fall in 

 the temperature breaks the circuit. 



O. Zabel J (1S67) placed in communication with an electric 

 thermometer a contrivance which consisted of two electro- 

 magnets acting on a hinged metallic screen. The completion 

 of the circuit by a rise in temperature placed the screen over the 

 flame, and thus checked the heat. 



J. Maistre 5 (1866I recommended an electric thermometer con- 

 nected with an electro-magnet, the armature of which could 

 remove the gas-burner from under the bath, or which could be 

 connected by means of a lever with the gas-supply tap. 



Springmuhl " (1S71) arranged an electro-magnet with a hinged 

 armature, so that on the completion of the circuit a weight 

 attached to a lever closed the gas-tap, which was not opened 

 until the release of the armature liberated a spring which acted 

 in the opposite direction. 



Vapour-tension Thermometers. — Appold's : consists of a glass 

 tube having a bulb at each end. The tube is filled, as also about 

 half of each bulb, with mercury ; the lower bulb containing ether 

 to the depth of half an inch, which floats on the mercury. The 

 tube is secured to a plate of boxwood, supported on knife- 

 edges, on which it turns freely. At the end of the plate, under- 

 neath the higher bulb, is a lever, which controls the supply-valve 

 of a gas-stove or the damper of a furnace. With a rise in the 

 temperature the increased tension of the ether-vapour drives 

 more mercury into the upper bulb ; this end then falls. With a 

 diminished temperature the reverse action takes place. 



Andreae's 8 (1878) is like Kemp's and various others, on the 

 principle of an U-tube with one limb closed. It is, however, 

 rendered more sensitive by the introduction of a certain quantity 

 of a volatile liquid into the air space. It must be borne in mind 

 that the liquid must be selected according to the temperature 

 required, as it is obvious that the regulator cannot be used in 

 any case where it has to be heated beyond the boiling-point of 

 the liquid. B ' 



Benoit 9 (1S79) constructed an apparatus in which he regulated 

 the temperature by adjusting the pressure on the volatile liquid 

 contained in the bulb. The following is the arrangement :— A 

 small reservoir, which can be shaped to suit the oven or bath in 

 which it is placed, holds the volatile liquid. This is connected 

 by means of a tube from the bottom, to which is attached an 

 india-rubber tube, to a regulator of the same pattern as that 

 used by Keichert. The regulator is fixed on a board which can 

 be raised or lowered, and is provided with two side tubes for 

 adding or drawing off mercury at will. 



By-pass. — Since it is obvious that in cases where the quantity 

 of gas required to pass through the regulator is large, any per- 

 ceptible increase in the pressure or the supply from the main 

 must be accompanied by a rise in the temperature of the bath, it 

 is advisable therefore to adjust the by-pass tap so that as small a 

 quantity as possible shall have to pass through the regulator. Here, 

 however, experience must decide how wide a margin must be left 



» Journ. Chem. Sac. i. 24 (1876). 

 3 Carl Repert, "Exp. Phys."iv. 

 88 (1868). 



t I'" 1 ; . Pc,y '- y°" r "- l8 «. =°2 ('867) : fres. Zcit. Anal. Chem. vii. 130. 

 5 Les Monties, x. 271 (1866). 



? H' ng - S elyt i y° ur "- «>'• J 4* ('87O I />«• Zeit. Anal. Chem. xi. 431. 

 I JJ"- Ro ?- ? K ~ *"'« (,8<56 >- * A ""- /v 'J>s- Chem. iv. 614 (1878). 

 9 Seance de la Sue. Franc, de Phys., 6 (1879). 



to the control of the regulator, for in some districts the differ- 

 ence between the day and evening pressures is so great that 

 adjustment becomes a matter of great difficulty. In some 

 laboratories, especially when near a suburban gas-works, the 

 day pressure is so low and the evening pressure is so high that 

 unless a pressure regulator be interposed between the main and 

 the temperature regulator, the by-pass cannot be used. 



Bunsen's 1 thermostat is the vessel in which he maintains a 

 constant temperature, and which is used by him in his vapour 

 density method. It consists of a sheet-copper cylinder, from 

 which at seven places equally distant from each other project 

 pairs of copper rods 7-8 mm. thick, which are riveted and 

 brazed into it. These rods are heated by gas flames, and the 

 temperature is adjusted by moving the burners to or from the 

 cylinder ; but in order to maintain it as constant as possible, 

 the apparatus must be carefully screened and the heights of 

 the flames kept nearly equal by means of a gas-regulator, and the 

 flames must reach a height sufficient to keep both the copper 

 rods in the middle part of the flame, and not to have the upper 

 rod heated only by the extreme point of the flame. 



Hipp's- (1S6S) regulator, which is de-crihed by Hirsch (and 

 is therefore sometimes referred to as Hirsch's), consists of a bent 

 compound metallic strap, steel on the outside and brass on the 

 inside. The ends thus approach with a falling temperature. The 

 one end is fixed securely inside the air-bath, and the free end 

 communicates by means of a fine copper wire with a regulating 

 screw which connects it with a bent rod carrying the gas-control 

 valve. 



Flow of Liquid. — Dupre and Page 3 (1S69). The water-bath 

 contains a coil of metal-tube like an ordinary condenser. The 

 lower end of this coil is connected with a second and smaller 

 worm, which is contained in a small water-bath. The latter is 

 heated by a lamp and kept gently boiling. The lower end of 

 this second worm is bent upwards and terminates in a long 

 funnel. Any water poured into this funnel will pass first 

 through the worm surrounded by boiling water, and be thus 

 heated, and then through the tube in the water-bath containing 

 the specific-gravity bottle. By regulating the flow of water the 

 temperature of this water-bath can be raised quickly, or kept 

 constant at any desired point. 



Strieker and Hurdon-Sanderson 4 (1870). — In this apparatus, 

 which is especially arranged for heating the stage of a micro- 

 scope, the temperature is adjusted by regulating the flow of 

 boiling water, through the hollow stage, by means of a com- 

 pression clamp. As the water in the small boiler is kept at a 

 constant level by means of an overflow, the supply when once 

 adjusted remains uniform. 



The exceedingly accurate method of maintaining a constant 

 temperature by controlling the pressure under which a liquid in 

 an outer casing is made to boil, is one that depends so essen- 

 tially on pressure that its consideration must be reserved for the 

 paper on Pressure-regulators. J. T. Brown 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE 

 Oxford — The establishment of the Waynflete Professor- 

 ship of Physiology was provided for by the late University 

 Commission, it being arranged that the emoluments of the 

 post should be paid out of the funds of Magdalen College, 

 to which college the Professor is to be attached as a 

 Fellow. Magdalen College had already shown interest in the 

 development of physiology, and has for some years past main- 

 tained a physiological laboratory, in which Mr. Yule, Fellow of 

 the College, has given courses of instruction in Practical Physio- 

 logy, open to all members of the University, and his lectures 

 have been attended by all candidates for honours in physiology, 

 such instruction not having been available elsewhere in Oxford. 

 Since the passing of the new statutes, the Linacre Professorship 

 has become confined to Human and Comparative Anatomy, and 

 there has been no University representative of physiology. The 

 want of a Professor of Physiology has lately been very strongly 

 felt, especially as the number of candidates in the subject 

 has much increased. It is understood that Magdalen Col- 

 lege, acting on the representations of the University to that 

 effect, has determined to apply such surplus funds as are avail- 



Ann.cxM. 273 (1867): Phil. Mag xxxiv. 1(1867). 

 = Carl Kepcrt. "Exp. Phys."iv. 201(1868); Dingl. polyt. Journ. exci. 

 366 (1869). 

 3 Phil. Trans. cUx. 608 (1869). « Q. J. Micro. Set., 366 (1870). 



